X4

Appendix: MPEG Encoder Settings 389
http://pro.magix.com
However, you can reduce the length of the GOP sequence (while
compromising the image quality at the same bit rate). This speeds up the
encoding process considerably as the motion estimation while encoding P and
B frames requires high CPU performance. The speed of decoding, i.e.
playback, is also increased.
If I frame is set to 1, each frame is an I frame. If the value is set larger, the
setting describes the total length of the GOP.
Auto GOP: Closed GOPs do not contain relations to frames from subsequent
GOPs. MPEGs where all GOPs are closed, make MPEG editing easier as the I
frames only can be edited alone if the GOP is closed. Auto GOP closes GOPs
at scene changes, whereby two different and complex procedures ("fast" and
"VSCD") are used.
Bit rate mode
In "constant bit rate" mode a bit rate that constantly remains the same is used.
This option should be used for Video CDs, as it is only required here. With a
constant bit rate the full power of MPEG compression can not be used
properly as bandwidth for non-moving scenes is lost.
"Variable bit rate" mode attempts to adjust the available storage space to the
requirements of the video you want to encode. The actual bit rate fluctuates
around a mean value. During calm sections of the video it may drop to a
minimum value, if there are movements in the scene it may rise to the
maximum value. There are two different regulation processes (mode 1 and
mode 128).
Advanced video settings
MPEG profile and level: The MPEG-2 standard defines so-called "profiles" and
"levels". For creating SVCDs and DVDs you can use "Main profile and Main
level". The high profile adds additional properties to the data stream like the
option to display an image at a reduced resolution for restricted transmission
quality (SNR-scalable profile), or locally scaled, for instance an HDTV data
stream on a standard TV set. The 4:2:2 profile is used if the image data is to
be encoded for alternative chroma scanning. However, these profiles are
supported by very few encoders, and mainly only for professional use.
These levels define the restrictions to the image resolution and the maximum
data rate. Low level can only reach a reduced resolution (352x2888 = CIF);
high level, or High 1440, enables encoding in HDTV format.